I think honestly this is the 3DS successor primarily. Now you'll ask "well what about the Wii U successor?" ... there isn't one.
This will replace the consoles too, Nintendo is happy enough with where mobile tech is today (and honestly mobile chips are capable of very pretty graphics these days) that they decided to just wash their hands of the separate console idea. Too many headaches with the console business and take two looks at Sony/MS trying to money-hat even third party DLC and I can see from Nintendo's POV why the traditional home console of today isn't up their alley at all.